Multi-directional strectchable nonwoven fabric



United States Patent 3,326,740 MULTl-DHRECTEONAL STRETCHABLE NONWOVENFABRHI Frederick F. Hand, Ridgewood, and Carlo Straclt, Clifton, NJ.,assignors to J. P. Stevens & Co., Inc, New York, N.Y., a corporation ofDelaware No Drawing. Filed Apr. 29, 1963, Ser. No. 276,148 2 Claims.(Cl. 161--170) ABSTRACT 0F THE DISCLOSURE This invention relates tononwoven fabrics. More particularly; the invention relates to nonwovenstretch fabrics. Nonwoven fabrics having the ability to stretch andrecover their original shape are useful in many segments ofthe clothingindustry. For example, nonwoven stretchable interlining is useful inbrassieres, Wool jersey garments, light-weight woolen fabrics, shoes,base fabrics for polyvinylchloride laminations, and the like. However,one

of the drawbacks of some of the presently known nonwoven fabrics residesin their inability to stretch in a number of directions at the same timeand substantially completely recover their original shape.

There exists, therefore, a need for nonwoven stretch fabrics whichexhibit multi-directional stretchability and substantially completerecovery of original shape. The present invention provides such amulti-directional nonwoven, stretchable fabric. In accordance with theinvention, 'a multi-directional, nonwoven, stretchable fabric comprises(1) thermoplastic bonding agent and (2) fibrous constituent selectedfrom the group consisting of (a) a blend of super-crimped fibrousmaterials and (b) a blend of a major proportion of super-crimped fibrousmaterials and a minor proportion of at least one component selected fromuncrirnped fibrous material, regular-crimped fibrous and mixtures ofuncrirnped and regular-crimped fibrous materials. It is to be understoodthat the term blend, as employed throughout this application and in theappended claims, means a mixture of at least two different fibrousmaterials, that is, for example, a mixture of nylon and acetate fibers.

Super-crimped, synthetic fibrous materials, which can be utilized in thepractice of the invention, include both natural and synthetic fibrousconstituents. Super-crimped, synthetic fibrous materials, which areuseful in the manufacture of a fabric made in accordance with theinstant invention, include nylons, acetates, polyesters, acrylates, andother crimpable, synthetic filamentary or fibrous materials and blendsthereof which have an average number of about 20 to about 40 crimps perinch and preferably about 25 'to crimps per inch. Super-crimped, naturalfibrous materials include wool, which has an average number of about 20to crimps per inch. The particular blends of these super-crimped,fibrous materials can vary as much as desirable when they are utilizedto prepare a fabric in accordance with the invention. However, in afabric manufactured in accordance herewith, the total amount of fibrousmaterial is normally in a range of about to 90 percent by weight, basedon the total fabric weight and preferably in a range of about 60 to 803,325,740 Patented June 20, 1967 percent by weight. On the other hand,greater or lesser amounts of fibrous material can be utilized, sincethese ranges are not critical, although the fabric so manufactured willnot then exhibit the most desirably preferred characteristics ofstretchability. In a fabric so prepared, the remainder of the fabricnormally comprises the thermoplastic bonding material generallymentioned hereinabove as well as other additives, such as anti-staticagents, dyes, thermosetting resins, which impart durability andresilience to the fabric, and/ or other additives and the like.

The regular-crimped component utilized in the practice of the inventioncan be any one or more of the synthetic or natural fibrous materialsmentioned hereinabove except that it contains an average number of about5 to 20 crimps per inch.

The uncrimped fibrous material can be any of the synthetic materialsmentioned above in an uncrirnped state or it can be natural fibrousmaterial. Fibrous materials of natural origin include materials such ascellulosic fibers, i.e. cotton and rayon, and proteinaceous fibers suchas wool, and the like. It is to be understood that the term uncrimpedincludes materials which contain an average number of 1 to 5 crimps perinch as well as materials which do not contain any measurable crimp.

The regular-crimped and uncrirnped fibrous materials may each beutilized alone in a blend of the super-crimped fibrous material or theymay be used in mixtures with each other in such a blend. However, it ispreferred that the total amount of regular-crimped and/or uncrirnpedmaterial be utilized in a minor amount in a range of about 2 to 40percent by weight, based on the total weight of fibrous material in afabric. Preferably, however, the total amount of regular-crimped and/oruncrirnped material is employed in a range of 5 to 15 percent by weight.Although the numerical ranges set out are not critical, and slightlygreater amounts of the uncrimvped and regular-crimped material can beemployed, a fabric containing greater amounts therein does not exhibitthe most desirably preferred stretch characteristics. On the other hand,in a fabric which contains very small amounts of regularcrimped and/oruncrirnped materials, the stretch characteristics exhibited are similarto a fabric which contains only a blend of super-crimped materialsalone.

The fibrous material employed in manufacturing the multi-directional,stretchable, nonwoven fabric in accordance with this invention can varyin denier size. In general, fibrous materials employed herein, Whetherthey be crimped or uncrirnped, have a denier measure ment in a range ofabout 1 to 15 denier per filament. Preferably, however, the fibrousmaterials employed herewith measure in a range of 1.5 to 8 denier perfilament. Moreover, it is to be noted that, in blends, fibrous materialsof different denier can be utilized. For example, an excellentmulti-directional, stretchable nonwoven fabric in accordance with theinvention comprises 35 percent by Weight of 3 denier per filament ofsupercrirnped nylon and 17.5 percent each of 3 and 5 denier per filamentof super-crimped acetate. In addition to the denier measurement, thefibrous material employed can also vary widely in the length ofindividual fibers thereof. For example, the particular nonwoven fabricreferred to immediately hereinabove contains individual filaments which'have an average length of approximately 1 /2 inches. However, individualfibers having an average length of anywhere from about /2 inch to about3 inches lend themselves very readily to utilization in the practice ofthis invention. Here, once more, although these figures are not of acritical nature, fabrics exhibiting the most desirable characteristicsin accordance with this invention are followed in manufacturing a fabricin accordance herewith. Moreover, processing limitations necessitate theuse of fibers not exceeding about 5 inches in length with presentlyknown machinery.

As pointed out hereinbefore, thermoplastic bonding agent is present inthe new nonwoven fabrics of this invention in a range of about to about50 percent by weight, based on the total weight of the fabric, andpreferably in a range of about to 40 percent by weight, although thesefigures are not critical. The thermoplastic material or binder can varywidely and depends to some degree upon the particular blend of fibrousmaterial being utilized to manufacture a fabric. The most particularlyuseful thermoplastic bonding agent for a particular blend of fibers canbe determined by standard analytical methods. Suitable thermoplasticbonding agents include polymers of esters and amides of acrylates andmethacrylic acids as well as polymers and copolymers of vinyl acetateand acrylic esters. Specific useful thermoplastic bonding agents are,butadiene-acrylonitrile copolymers, butadiene-styrene copolymers,carboxylated butadienestyrene copolymers, natural rubber, carboxylatedbutadiene-acrylonit'rile copolymers, styrene-acrylate copolymers, butylrubber, polyurethanes, polyethylene emul sions, polyvinyl chlorideemulsions, polyvinyl acetate dispersions, copolymers of polyvinylchloride polyvinyl acetate, acrylic-vinyl acetate copolymers,homopolymeric vinylidine chloride, polyvinyl acetate stearate;terpolymers of polyvinyl acetate, vinylidine-chloride and acrylonitrile;polyvinyl but ral and polyvinyl acetate dibutyl maleate. Also useful asbonding agents are terpolymers and copolymers of acrylates and acrylicacids.

The thermoplastic bonding agent is normally employed in an aqueoussolution or emulsions of about 10 to 50 percent concentration. Thesolution or emulsion also contains thermosetting resins, such asmelamine-formaldehyde resins to impart durability and resilience to thefabric. The solution or emulsion also contains a latent acid catalyst,such as ammonium chloride, or the like.

The multi-directional, stretchable, nonwoven fabrics of this inventioncan be manufactured by any of the known methods for making nonwovenmaterials and such a fabric consists primarily of a fibrous web which isproduced on a card, garnett or Rando-Webber apparatus. Generally, such aprocess includes opening the fiber on fiberopening machinery,preparation and formation of the web under proper temperature andconditions of humidity and, finally, bonding the web by saturating,spraying, impregnating, or other application.

The web-forming process usually begins with opening of the fibers. Thisoperation may include a procedure of blending different fibers beforeloading them into a picker from where they are conveyed to a ga'rnett orother web-forming device. The fiber-opening operation can beaccomplished by equipment such as shredders, beaters, grinders,aerators, automatic blending feeders and remix blenders. After thefibrous material has been opened and blended, it is delivered directlyto a web former. Although garnetts usually are regarded as web formers,they are sometimes useful in the opening operations as a precardingmachine to achieve more thorough opening and blending before webformation.

In general, web formation can be achieved by three fundamentallydifferent processes. Two of these are parallel and crossload webproduction. The other is the production of random or isotropic webs byair blowing. Currently, commercial nonwoven webs are manufactured by allthree types of processes.

The parallel laid webs, in which all fibers run in approximately thesame direction, are produced on carding machines such as garnetts,cards, and the like, which are devices for combing the fibers intoessentially parallel arrangement. Each carding machine delivers a thinsheet of parallel fibers onto a continuous belt. Several such machinesare run in series and the thin layers produced by successive machinesare super-imposed on each other running in the same direction to form amulti-layer web.

The crosslaid web is a system in which the web is built up in sandwichfashion in a sequence of layers in which the fibers run in differentdirections. Again the fibers is first run through a carding machine toform a thin sheet of parallel fibers. However, the product of successlvecarding machines is delivered onto the conveyor belt in differentdirections. Thus, the first carding machine delivers in the direction ofconvey-or travel. The sheet delivered from the second carding machine issuperimposed crosswise to the first layer by means of a cross lapper,also known as a Scotch Feeder. The result is a plurality of superimposedlayers of fibers webs.

One process of manufacturing random laid webs include-s process steps inwhich the fibers are opened up and are blown onto a rotating perforateddrum or moving foraminous conveyor belt to which they are held byinternal vacuum. A mat is formed thereby and delivered to a high-speedlickerin (a rotating drum provided with metallic teeth which breaks upthe original web structure). The resulting fibrous particles are blownonto a second vacuum drum where they form a highly uniform web which istaken off and passed to a continuous conveyor.

The final operation in any of the processes is the bonding orstabilization of the fibrous mat. This is done by applying binder to theunbonded web such as by impregnation, spraying, coating and the like.

After drying the bonded nonwoven fabric, finishes can be appliedthereto, if some special properties are required. Among commonly knownfinishes which are applied to a nonwoven fabric are water-repellencytreatments, fireretarding treatments, pigmenting treatments, softeningtreatments, and the like. Subsequently, any cross-linking agents whichhave been heretofore added to impart durability and resilience to thefabric can be activated by subjecting the fabric to elevatedtemperatures (about 140 C. to 160 C.) at this stage of the manufacturingprocess.

In order to illustrate the instant invention more fully, the followingexamples are set forth. In the examples all parts and percentages are byweight unless otherwise indicated.

EXAMPLE I A nonwoven fabric was prepared in accordance with thefollowing procedure: A mixture of percent by weight of nylon staplefibers (polyhexamethylene adipamide), which had an average length ofapproximately 1 /2 inches and a denier measurement of 3 denier perfilament and about 30 crimps per inch and 50 percent by weight ofacetate staple fibers (cellulose acetate) which had an average length ofapproximately 1% inches, a denier measurement of about 3 denier perfilament and approximately 30 crimps per inch, were thoroughly preopenedand blended together on a blender-opener. The blended materials werethen conveyed to a Rando-Webber and formed into a mat of random-laidfibers having a thickness of about 10 mm. and weighing approximatelygrams per square yard. The web-forming operation as well as the blendingand fiber-opening steps were carried out at room temperature (about 20C.) and a relative humidity of approximately percent. The uniform web soformed was then bonded by passing the fibrous mat between a metallicscreen and a perforated, stainless steel drum, both of which guide theunbonded web into a solution of bonding agent which contained, byweight, about 220 parts of thermoplastic, polymeric acrylic emulsion ofwhich 99 parts by weight are polymer solids and 274 parts by weight arewater. The bonding solution also contained 2 parts by weight of a liquidtriazine-formaldehyde resin in 50 percent solution as a cross-linkingagent and 2 parts by weight of ammonium chloride catalyst. The bindingsolution further contained 2 parts by Weight of alkyl aryl polyetheralcohol as a wetting agent. After thoroughly immersing the web in thesolution of bonding agent, it was conveyed over a vacuum box whereexcessive binder was removed from the fibrous web. The fibrous web washeated to a temperature of approximately 125 C. to aid in removingexcess binder therefrom and was then passed through a heating zone at atemperature of approximately 150 C. for about 2 to 3 minutes in order tocure the treated fabric. The nonwoven fabric so formed possesses theability to be stretched in a multiple number of directions at the sametime and to return to its original shape and contains approximately 70percent by weight of fibrous material and 30 percent by weight of solidbinder.

EXAMPLE II The procedure of Example I was repeated except that thenonwoven fabric which was made contained 50 percent by weight of nylonstaple fibers (polyhexamethylene adipamide) which had an average lengthof approximately 1 /2 inches, a denier measurement of 3 denier perfilament and about 30 crimps per square inch, 35 percent by Weight ofacetate staple fibers (cellulose acetate) which had an average length ofapproximately 1%; inches, a denier measurement of 3 denier per filamentand approximately 30 crimps per inch and 15 percent by weight ofuncrimped nylon staple fibers, such as those mentioned above, but havinga denier measurement of about 2.8 denier per filament. As with thenonwoven fabric prepared in Example I, this fabric exhibited goodqualities of multi-directional stretchability and return to originalshape and contained approximately 70 percent by weight of fibrousmaterial and 30 percent by weight of the solid binder.

EXAMPLE III The procedure of the foregoing examples was repeated and afabric was prepared which contained 50 percent by weight of nylon staplefibers (polyhexamethylene adipamide) which had an average length ofapproximately 1 /2 inches, a denier measurement of 3 denier per filamentand about 30 crimps per inch, 35 percent by weight of acetate staplefibers (cellulose acetate) which had an average length of approximately1%; inches, a denier measurement of 3 denier per filament andapproximately 30 crimps per inch and 15 percent by weight of nylonstaple fibers such as those mentioned above which had an average lengthof approximately 1 /2 inches, a denier measurement of 3 denier perfilament and approximately crimps per inch. In lieu of the solution ofbinding agent in the foregoing examples, the thermoplastic acrylicemulsion polymer was replaced by a carboxy modified polymericbutadiene-acrylonitrile bonding agent which was employed in a solutionof 198 parts which contained about 99 parts by weight of the polymericsolids. As with the fabrics prepared in Examples I and II, the nonwovenfabric of this example exhibited excellent properties ofmulti-directional stretchability as well as ease of processing andcontained about 70 percent by weight of fibrous material and about 30percent by weight of solid binder.

EXAMPLE IV The procedure of the foregoing examples was once morerepeated except that there was employed to make the nonwoven fabric 50percent by weight of nylon staple fibers (polyhexamethylene adipamide)of an average length of approximately 1% inches, a denier measurement of3 denier per filament and about 30 crimps per inch, 30 percent by weightof acetate staple fibers (cellulose acetate) of an average length ofapproximately 1%;

inches, a denier measurement of 3 denier per filament and approximately30 crimps per inch, 10 percent by weight of uncrimped nylon staplefibers which had a denier measurement of about 2.8 denier per filamentand approximately l /2 inches in length and, finally, 10 percent byweight of nylon staple fibers having the same length and deniermeasurements but which contained only about 10 crimps per inch. Thefibrous web formed from the blend was bonded together in the same manneras in the foregoing examples and the carboxy modified polymericbutadiene-acrylonitrile bonding agent employed in Example III was oncemore utilized. The resulting nonwoven fabric exhibited excellentproperties of multi-directional stretchability and containedapproximately percent by weight of fibrous material and 35 percent byweight of solid binder.

The nonwoven fabrics made in accordance With the preceding examplesexhibited excellent properties of stretchability and recovery to normalshape in comparison to like fabrics which contained the same materialsbut which had a normal amount of crimp.

The fabrics prepared in accordance with the present invention exhibitmany desirable characteristics. They are especially adapted for use inall areas where a nonwoven stretch fabric is generally employed and havethe ability to stretch in a multiple number of directions andsubstantially return to their normal shape. More-over, this property ofstretchability is relatively permanent, i.e., it generally endures forthe life of the fabric.

It is to be understood by those skilled in the art that many apparentlywidely different embodiments of this invention can be made withoutdeparting from the spirit and scope thereof. Accordingly, it is to beunderstood that this invention is not to be limited to the specificembodiments thereof, except as defined in the appended claims.

What is claimed is:'

1. A nonwoven fabric which exhibits multi-directional stretchability andsubstantially complete recovery of original shape, said fabriccomprising from 10 to 35 percent by weight of said fabric of acarboxylated polymeric butadiene-styrene bonding agent, from to 50percent by weight of said fabric of a blend of nylon and acetate stapleshaving from 20 to 40 crimps per inch and from 5 to 15 percent by weightof said fabric of nylon staples having less than 20 crimps per inch.

2. A nonwoven fabric which exhibits multi-directional stretchability andsubstantially complete recovery of original shape, said fabricconsisting essentially of a carboxylated polymeric butadiene-styrenebonding agent and a stable fibrous material, comprising a blend having amajor portion of nylon and acetate staples having from 20 to 40 crimpsper inch and a minor portion of nylon staples having less than 20*crimps per inch.

1. A NONWOVEN FABRIC WHICH EXHIBITS MULTI-DIRECTIONAL STETCHABILITY ANDSUBSTANTIALLY COMPLETE RECOVERY OF ORIGNAL SHAPE, SAID FABRIC COMPRISINGFROM 10 TO 35 PERCENT BY WEIGHT OF SAID FABRIC OF A CARBOXYLANTEDPOLYMERIC BUTADIENE-STYRENE BONDING AGENT, FROM 85 TO 50 PERCENT BYWEIGHT OF SAID FABRIC OF A BLEND OF NYLON AND ACETATE STAPLES HAVINGFROM 20 TO 40 CRIMPS PER INCH AND FROM 5 TO 15 PERCENT BY WEIGHT OF SAIDFABRIC OF NYLON STAPLES HAVING LESS THAN 20 CRIMPS PER INCH.